Safer, less toxic propellants that meet operational performance requirements have long been sought by the propulsion industry. The commitment to increasingly safer and lower cost orbit space operations, as evidenced by a central charter of the Space Launch Initiative, has made success in testing less toxic propellants more imperative than ever. Less toxic propulsion systems are being developed to replace engine systems that use more hazardous propellants, such as Nitrogen Tetroxide (NTO) and Monomethyl Hydrazine (MMH).
Hydrogen peroxide offers many potential benefits as a non-toxic propellant source for target, space, and on-orbit applications. Hydrogen peroxide can be decomposed by passing it over a catalyst. The catalyst bed decomposes the hydrogen peroxide to produce super-heated steam and oxygen. The hot gases can be used to drive gas turbines, provide thrust as a monopropellant, provide an oxidizer for bi-propellant systems, or function as an igniter for a rocket engine when combined with fuels like kerosene.
Ninety-eight (98%) percent hydrogen peroxide is an excellent oxidizer for many space applications, both in monopropellant and bipropellant systems, because it is non-cryogenic, has high density, and can be used as a regenerative coolant. However, the high adiabatic decomposition temperature of 98% hydrogen peroxide (1734 degrees Fahrenheit at one atmosphere, versus 1364 degrees Fahrenheit for 90% hydrogen peroxide) causes melting of conventional catalyst systems currently used to decompose 90% hydrogen peroxide.
Beyond traditional silver catalysts, many catalysts are already known for the decomposition of hydrogen peroxide. Metals such as gold, platinum and palladium, in addition to oxides such as manganese dioxide are known to be active catalysts for the decomposition of hydrogen peroxide. However, these catalysts have performance limitations in the decomposition of high concentrations of hydrogen peroxide. These limitations include low melting temperatures, low activity and sensitivity to stabilizers contained in the hydrogen peroxide solutions.
Therefore, there is a need for developing a catalyst system with enhanced temperature capability, high activity and low sensitivity to stabilizers that can safely operate with up to about 99% concentration hydrogen peroxide propellant systems.
Further, a similar need exists for catalyst systems that may be used for the catalytic combustion of hydrocarbon/air mixtures. Such a catalyst system could be used in the power generation or automotive industries for emission control applications.